1. Field of the Art
This invention relates to polyarylenesulfide (hereinafter referred to as PAS) complexes, processes for production thereof, and uses thereof.
Of PAS resins, poly-p-phenylenesulfide (hereinafter referred to as PPS) is characterized by excellent properties such as resistance to heat and chemicals, mechanical properties, and fire resistance, and has been broadly used in the field of injection molded articles, etc.
It is not easy, however, to obtain the PPS polymer having a high molecular weight or a high melt viscosity, by simple polymerization steps for production thereof.
The PPS having low melt viscosity has been widely used for injection molding. The PPS having high melt viscosity is needed in the case of high-impact or thick molded articles. Moreover, in the field of extruded products which are also important and especially in the field of sheets and films, PPS having high melt viscosity is needed from the viewpoint of processability and properties of formed products.
2. Prior Art
A variety of research has been conducted to obtain PPS of high melt viscosity on such backgrounds. For example, the following methods have heretofore been known: (1) a method for increasing the molecular weight of PPS by conducting the polymerization reaction of paradichlorobenzene with sodium sulfide in N-methylpyrrolidone (hereinafter referred to as NMP) in the presence of sodium acetate or lithium acetate (Japanese Patent Publication No. 12240/1977); (2) a method wherein a multifunctional crosslinking agent such as trichlorobenzene is used in the polymerization (Japanese Laid-open Patent Application No. 136100/1978); and (3) a method for increasing melt viscosity by heat-treating PPS powder at a high temperature in the presence of oxygen (Japanese Patent Publication No. 30609/1977, Japanese Laid-open Patent Application No. 119926/1982), etc.
As far as known by the present inventors, however, all these methods have some problems. In the method (1), there is a limit of increasing the melt viscosity. The melt viscosity will not reach a level high enough for obtaining sheets, films and the like having good properties. Moreover, the method entails a problem due to the use of such a lot of costly salts such as lithium salts that the salts should be recovered from the waste water. In the method (2), PPS of high viscosity can be obtained by the use of a large amount of crosslinking agents. The resulting PPS, however, has no linearity and results in brittle products having little elongation. When it is formed into yarns or films, the processing is difficult because of poor spinnability or stretching property. The resulting products fail to have good properties even when they are obtained. Also in the method (3), PPS of high viscosity can be obtained with sufficient treatment at a high temperature (e.g. 200.degree. C. or higher). It is difficult to conduct uniform reaction, whereby locally overheated portions are often formed. Such non-uniform treatment causes fish eyes and uneven molecular orientation in the case of films, and also uneven stretching, nonuniform thickness, slabbing, breaking and the like in the case of yarns or filaments. Moreover, such treated PPS has problems such as poor spinnability and stretching property as in the resin treated by the above mentioned method (2), because the method (3) may also crosslink the PPS.
On the other hand, it is also known to produce compositions for enhancing the mechanical properties of PAS by adding to PAS the powder, particles, fibers or the like of inorganic compounds, metal compounds, etc. such as alumina, silica, titanium compounds, glass and graphite. These additives, however, are inert compounds and have no chemical interaction with PAS. Thus, the melt viscosity of PAS could not be enhanced by addition of these additives.
Moreover, Japanese Laid-open Patent Application No. 78257/1984 Specification discloses a method for affecting crystallization of PAS by treating PAS at an elevated temperature in an aqueous solution of calcium oxide or the like. It is difficult, however, to markedly enhance the melt viscosity of PAS.